Method and apparatus adapted to feed in pulsating manner into a chamber subjected to periodic pressure variations a substance capable of flowing



Aprll 17, 1962 M. MAY

METHOD AND APPARATUS ADAPTED TO FEED IN PULSATING MANNER INTO A CHAMBER SUBJECTED TO PERIODIC PRESSURE VARIATIONS A SUBSTANCE CAPABLE OF FLOWING Filed July 11, 1958 Fig, 1 gas INVENTQR MICHAEL MAY B W a) ATTORNEYS Unite This invention relates to a method of pulsating feeding, into a chamber subjected to periodic pressure changes, a substance capable of flowing, and has further for its object an apparatus for carrying out the method, together with an application of the same.

The method according to the invention principally consists in that, during a pressure period in said chamber, the substance is brought to a substantially constant pressure which is at least as high as the mean value of the pressure prevailing in the chamber, the substance being then brought into the chamber in controlled dependence on a heavily damped (aperiodic) oscillating system which is induced to oscillate at the same frequency by the pressure variations in the chamber.

The apparatus suitable for applying the method as per iuventionis principally characterized by a pressure gen States Patent Q orator for the substance to be brought in, at least one ini let opening for bringing the substance into the chamber, and an osci la lng system subjected to pressure variations in the chamber, Whose oscillating movements control the passage of the substance through the inlet opening.

A preferred application of the method according to the invention lies in the injection of fuel into the combustion chambers of internal combustion engines.

In known LC. engines with fuel injection, an injection pump has heretofore been used which, each time at the proper moment, feeds under high pressure into the socalled injection nozzle a definite amount of fuel suited to the momentarily required output of the machine. The injection pump generally includes ported piston elements which are actuated by cams driven by the engine itself. As a result, a considerable technical and financial expenditure must on the one hand be made for each combustion chamber, and on the other hand, conditioned by the mechanically relatively complicated structure, the speed of the LC. engine cannot be increased beyond a certain amount which today is often considered too low. The functioning of the apparatus is further complicated when using fuels of poor lubricating quality, such as gasoline, benzol, alcohol, etc. With usual prior art methods, the adoption of a gaseous fuel is inconceivable.

A primary object of the present invention is to remove the aforementioned shortcomings.

Further features of the invention will appear from the claims, description and accompanying drawing which shows by way of example some forms of embodiment of the apparatus according to the invention, with reference to which the method according to the invention is explained hereinafter.

in said drawing:

FIG. 1 shows a cross-section of a two-cycle engine with pertinent apparatus (only diagrammatically represented) for injecting a liquid fuel into the illustrated combustion chamber of the engine;

PEG. 2 shows a second form of a detail of the apparatus, partly in view and partly in axial section;

FIG. 3 shows an axial section of a third form of the same detail;

FIG. 4 is the similar representation of a fourth form of the same detail;

FIG. 5 shows a part of the same object as seen from the left in FIG. 4; and

3,029,799 Patented Apr. 17, 1962 FIG. 6 is a cross-sectional view of a further modification.

Referring more particularly to FIG. 1, a cylinder 11 (only diagrammatically represented) has a piston 12 axially guided therein which is connected in the usual way to a crankshaft 14 by means of a connecting rod 13. Into the crankcase 15 an air inlet pipe 16 opens, having located therein an adjustable throttle valve 17 and a pressure box 18 for registration of variations of pressure. A by-pass 19 directs the air, compressed in the crankcase 15 during the down-stroke of the piston, into the combustion chamber fit) of the cylinder 11, when the piston 12 passes through its bottom dead centre. At about the same time, the piston 12 uncovers the opening of an exhaust pipe 21. The cylinder head 11 houses a spark plug 22 and an inlet 23 for liquid fuel.

The inlet 23 is the opening for an inlet duct 24 which is continuously connected to the combustion chamber 20 with an oscillation chamber 25, the diameter of which is much larger than that of the inlet duct 24. The inlet duct 24 and the oscillation chamber 25 are arranged in a casing 26 which is detachably mounted on the cylinder head. At the top of the casing 25 is closed by a screw-plug 2'7. Into the oscillation chamber 25 a fuel pipe 23 opens. In the oscillation chamber 25 there is a quantity of liquid fuel, having over its surface a gas cushion 29, say, an air cushion, which is elastically yieldable owing to the compressibility of the gases. The fuel quantity present in said chamber, together with the gas cushion 29, constitute a heavily damped, almost aperiodic oscillating system which is induced to oscillate through the inlet duct 25 by means of the periodic pressure variations in the combustion chamber 29. The damping of the oscillating system is mainly effected by the narrow duct 24.

The liquid fuel flows from a storage tank 51 to a filter 32, whence to a pump 33 which preferably works continuously and brings the fuel to a substantially constant pressure which is higher than the mean value of the pressure prevailing in the combustion chamber 26 at maxi mum torque of the LC. engine. Joined to the pressure side of the pump '33 is a pressure equalizer 34 adapted, by means of an air cushion, to intercept and equalize pressure surges that may arise. The pressureequalizer 34 also communicates with the suction side of the pump 33 through an adjustable return valve 35 in order that any excess quantity delivered by the pump can flow back to the suction side. The delivery side of the pump 33 communicates further with a pressure reduction member 36 which is adjustable for regulating the output of the LC. engine. From said member 36, the fuel flows into the aforementioned pipe to which is connected a control pressure gauge 37, if required. Numeral 33 designates a distributor (shown diagrammatically) from which the fuel also flows thru the inlet ducts 230 to other cylinders Zita of the LC. engine, when of the multi-cyiinder type. Inserted in the fuel pipe 23, between distributor 38 and casing 26, is a pressure equalizer 39 which, for instance, contains an air cushion. I

As indicated in chain dotted lines, a pedal 41 is operatively connected to the variable pressure reduction member 36 as well as to the throttle valve 17. But said member 36 is also automatically controlled by the pressure box 13 and/or by the speed of the crankshaft 14, as also shown chain dotted.

The described apparatus for injecting fuel into the combustion chamber 20 works according to the following method:

By means of the elements 3546 and 39, in the fuel pipe 23 a substantially constant pressure is produced which may be checked at the gauge 37. On an average, the air cushion 2h in the oscillation chamber 25 is always somewhat compressed. The periodic pressure variations in the chamber 20 act through the inlet duct 25 also upon the fuel quantity present in the oscillation chamber 25 so that this fuel, being supported against the air cushion 29 in the chamber 25 and partly also in the duct, oscillates up and down at the working frequency of the piston 12, but with a certain lag or phase displacement with respect to the movement of the piston. The time-lag or phase displacement of the oscillating system with respect to the momentary pressure in the cylinder is mainly achieved by the throttling action of the comparatively narrow duct 24 and determined by the cross-sectional area, length and surface properties of the duct 24, as well as by the modulus of elasticity of the yielding cushion 29.

When, during a combustion occurring in the chamber 20, the piston 12 starts to move downwards, the highest momentary pressure prevails in chamber 20. This drives the liquid fuel in the duct 24 and in the oscillation chamber 25 upwards with a certain lag, whereby the air cushion 29 will be heavily compressed. The diameter of the inlet duct 24 is so small that, besides fuel, no gas bubbles can pass therethrough. As the piston 12 passes through its bottom dead centrethe pressure in the combustion chamber 20 consequently falling to a minimum which is only slightly above atmosphericthe liquid fuel in the oscillation chamber 25 still moves upwards because of its inertia. Not until the piston 12 has started its up-stroke and closed the openings of the by-pass 19 and exhaust pipe 21 will the compressed air cushion 2% re-expand, thus causing the fuel in the oscillation chamber 25 to go down. Because of inertia, the fuel in chamber 25 oscillates beyond the position corresponding to the mean pressure of the air cushion 29. Incidentally a certain amount of the fuel passes through the inlet duct 23 into the combustion chamber 20, where the fuel is distributed in the compressed air and mixed therewith. From the pipe 28 fresh fuel flows again into the chamber 25. As the piston 12 passes through its top dead centre, ignition of the fuel/ air mixtures occurs by the spark plug 22, whereupon the described operations will repeat.

The pressure equalizer 39 prevents the pressure variations in chamber 25 from reacting on the fuel pipes 225 which lead from the distributor 38 to the other cylinders of the LC. engine. For the same purpose, the fuel pipes 23 themselves may exert a throttling action, in that said pipes have a plurality of cross-sectional constrictions 28a and widenings 28!) arranged one after the other. See FIG. 3. The fuel pipe 28 may have a plurality of constrictions 2% (FIG. 6).

By adjustment of the pedal 41, the output of the LC. engine may be regulated, whereby both the pressure reduction member 3a and throttle valve 17 are adjusted. A higher pressure in the fuel pipe 28 has for its effect that, in each operating cycle of the piston 12, a larger quantity of fuel is injected into the combustion chamber 20.

One advantage of the described method is that the fuel, on leaving the pressure reduction member 36, need not have so high a pressure as had each time to be momentarily produced in the usual prior art injection pumps. It suffices if the pressure of the fuel in the pipe 23 lies comparatively little above the mean value of the pressure in the combustion chamber 20. Injection of fuel into the chamber 20 occurs indeed under a higher pressure which is composed of the sum of the pressure in the fuel pipe 28 and the pressure which results from the kinetic energy of the oscillating system in the chamber 25.

Another advantage of the method and the described apparatus resides in the factthat an injection pump of the conventional comparatively complicated type is not required and that cam-controlled valves and pressure pistons are done away with.

In the form of embodiment according to FIG. 2, the inlet duct 24 is located within an adapter nipple 45 detachably and exchangeably inserted in a casing 26a which is removably screwed into the cylinder head (not shown) by means of a threaded portion 46. Inserted from top into the casing 26a is a screw-plug 27:: having an axial bore 47 and at least one radial bore 48. Located between the top of the casing 26a and the head of the screw-plug 27a, by interposition of gaskets 49, is a ring member 50 having an inwardly open annular groove 51 which communicates with the radial bore 43. Said ring member 50 has a nipple 52 for connection to the fuel pipe 28. The fuel flows through the groove 51, radial bore 43 and axial bore 47 into the oscillation chamber 25 of the casing 2611. Between the surface of the fuel and the screw-plug 270 there is again the air cushion 29 which, in this case, surrounds a tapered extension of said screw-plug. The action is the same as in the form according to FIG. 1. The principal advantage over FIG. 1 lies in the exchangeability of the nipple 45 which has the inlet duct 24. It is therefore possible to choose the inlet duct 24 in its diameter and length to suit the fuel used and the average speed of the I.C. engine. Diameter and length as well as the surface finish of the duct 24 may, if necessary, be advantangeously of such dimensions that the duct 24 represents a resonant pipe for the pressure-change frequency in the combustion chamber 20.

In the form according to FIG. 3, the casing 26b has, instead of a screwed portion, a flange 55 mounted on the cylinder head by means of screw bolts (not shown). By means of a nipple 52, the fuel pipe 23 is joined to the side of the casing 26b, the top of which is closed by a screw-plug 27b. The interior 25 of the casing 25b contanis a screwed-in partition wall 56 which is located between the level of the fuel and the screwplug 27b, and has a comparatively narrow passage way 27. This partition 56 forms an additional damping for the air cushion 29 which is at both sides thereof. Said passage way offers resistance to the air flowing through so that compressing and expanding of the air present between partition 36 and screw-plug 27b occurs with a certain timelag. The inlet 23 has associated therewith a closing member 58 provided on a lengthwise grooved stem 59 which protrudes through the duct 24 and is under the influence of a compression spring 60 situated within the oscillation chamber 25. The spring 60 tends to keep said member 58 in its closed position. The elements 58-60 form parts of the oscillation system which is induced to oscillate by the pressure variations in combustion chamber 20. During the injection of fuel, the closing member 58 opens automatically under the pressure action of the fuel, but only when the fuel pressure has reached a minimum value overcoming the power of the spring 60. During combustion in chamber 20, the closing member 58 automatically resumes its closed position, after the quantity of fuel in chamber 25 has again received an upwardly directed impulse. Hence, during each pressure-change period in the combustion chamber 20 the closing member 58 goes once into the open position. The member 58 causes that the fuel is injected through the inlet 23 and well distributed In the combustion chamber only with higher pressure and with greater velocity.

The form of embodiment according to FIGS. 4 and 5 comprises a casing 260 which is attached to the side of the cylinder head by means of flanges 550. Two horizontal inlet ducts 24a and 24b are provided, each with an inlet 23a and 2311 respectively, opening into the combustion chamber 20. At top the hollow space 25 of the casing 26c is closed by a screw-plug 27, whereas the fuel pipe is joined to the bottom of the hollow space 25 by a nipple 520. Between the fuel surface and screwplug 27 there is again the air cushion 20. In principle, the action is the same as in the first form.

The embodiment illustrated in FIGURE 6 shows a casing 26d, the form of which is essentially similar to the casing 260 of FIGURES 4 and 5. The casing 26d is attached in the same way to a cylinder head of an internal combustion engine as above described with regard to FIGURES 4 and 5.

Two inlet ducts 24c and 24d are arranged in a way so that they diverge against the combustion chamber in the cylinder which is not shown, in order that a better distribution of the injected liquid fuel can be obtained. The fuel pipe 23 terminates at the bottom into a hollow space 25 of the casing 26:! and is fastened by means of a nipple 520.

The hollow space 25 is closed at the top by a flexible membrane 55 which is kept tight at its circumference by means of a threaded ring 56 which is screwed onto the casing 26d. ,The exterior side of the membrane 55 from the hollow space is under atmospheric pressure. The membrane 55 forms a flexible wall for the limitation of the space 25, in which a certain amount of the liquid fuel is present. Contrary to the preceding example, the hollow space 25 is practically completely filled with fluid. Instead of an air cushion, another elastical flexible cushion is present which is formed by the membrane 55 and the atmospheric pressure.

The already mentioned heating of the fuel in this case is arranged at the inlet ducts 24c and 24d and occurs for example with an electrical heating wire 57.

The fuel need not in all cases be a liquid, inasmuch as the described method and related apparatus will also work when using a gaseous fuel. In this case, the quantity of gas filling the oscillation chamber 25 and inlet duct 24 will constitute the oscillating system which is caused to make compressing and expanding oscillations by the pressure variations in the combustion chamber 20.

If the LC. engine includes a plurality of cylinders and one of them ceases to work for some reason, for instance owing to misfire or insutficient compression, flooding of the respective cylinder due to continual subsequent delivery of fuel may be avoided for example by fitting into the opening of the pipes 28 automatically acting valve whose sectional area of flow automatically changes inversely proportional to the average working pressure in the respective cylinder.

The LC. engine need not necessarily be of the twocycle type.

It will be understood that this invention is not limited to the specific designs of bringing a fuel into the combustion chambers of LC. engines, as it may be employed wherever a substance capable of flowing shall be brought into a chamber subjected to periodic changes in pressure. As an example of such application may be mentioned the feeding of a lubricant to a crankshaft or to a reciprocating piston.

Having thus described my invention, I claim:

1. In combination a compression chamber of a piston engine having at least one piston, a pressure generator for bringing a fluid to a substantially constant pressure to be fed into said compression chamber, said pressure being at least as high as the mean value of the pressure prevailing in said compression chamber during each stroke cycle of the piston, said compression chamber having at least one inlet for bringing said fluid into said compression chamber, a quantity of said fluid and an elastically yielding cushion forming an oscillating system, an oscil lation chamber containing said quantity of fluid and connected to said compression chamber by said inlet, a delivery pipe for said fluid connecting said pressure generator with said oscillation chamber, said inlet and said delivery pipe being of smaller cross-section than said oscillation chamber, said oscillating system being coupled with the pressure variations in said compression chamber through said inlet to cause said oscillating system to oscillate with the same frequency as said pressure variations but with a time-lag due to said inlet.

2. Apparatus according to claim 1, wherein the oscillation chamber also includes the elastically yielding cushion.

3. Apparatus according to claim 1, wherein said elastically yielding cushion is a gas cushion.

4. Apparatus according to claim 1, wherein said elastically yielding cushion is formed by an elastically yielding wall adjacent the mentioned quantity of fluid.

5. Apparatus according to claim 1 wherein said inlet is the opening of a duct which is constantly open towards said compression chamber and oscillation chamber.

6. Apparatus according to claim 5, wherein the fluid is a liquid and the diameter of the inlet duct such that no gas bubbles can pass therethrough in addition to the fluid.

7. Apparatus according to claim 6 wherein said inlet duct represents a resonant pipe for the frequency of said pressure variations in said compression chamber.

8. Apparatus according to claim 1, wherein said inlet has associated therewith a closing member as part of the oscillating system and moving to the open position once in each oscillating period.

9. Apparatus according to claim 1, wherein said inlet and said pressure generator hav a pressure equalizer located therebetween.

10. Apparatus according to claim 1, wherein said pressure generator includes at least one pump bringing the fuel up to a pressure higher than the mean value of the pressure prevailing in the compression chamber at full output of said engine, said pump and inlet having inserted therebetween a variable pressure reduction member for regulating the output of said engine.

11. Apparatus according to claim 1, wherein means are provided for varying the pressure of the fuel fed to the oscillation chamber for regulating the output of said engine.

12. Apparatus according to claim 1, wherein at least two inlets are provided diverging towards said compression chamber.

13. Apparatus according to claim 1 wherein a plurality of'compression chambers with at least one inlet for each compression chamber and pertinent oscillating system has associated therewith a common pressure generator leading the fluid through a distributor to the in dividual inlets.

14. Apparatus according to claim 13, wherein the distributor and the individual inlets have inserted therebetween pipes with throttling action.

15. Method of pulsating feeding a fluid into a compression chamber of a piston engine subjected to periodic pressure variations, said fluid being first brought to a substantially constant pressure at least as high as the mean value of the pressure prevailing in the compression chamber and then fed into an oscillation chamber connected to said compression chamber, a certain quantity of said fluid in said oscillation chamber being used as the mass of an oscillating system induced to oscillate at the same frequency as the pressure variations in said compression chamber but with a certain time-lag, said oscillations causing the pulsating feeding of said fluid from said oscillation chamber into said compression chamber while a corresponding quantity of fluid is flowing into said oscillation chamber.

16. Method according to claim 15, wherein said quantity of fluid in the oscillation chamber and an elastic cushion adjacent to said quantity ar used as oscillating system.

17. Method according to claim 15, wherein the fluid is at first brought up to a pressure lying above the mean value of the pressure prevailing in said compression chamber, and subsequently fed to the oscillating system through an adjustable pressure reduction member.

References Cited in the file of this patent UNITED STATES PATENTS 

